#include"mrrr.h"

/* Subroutine */int pdlarrj(int *n, double *d__, double *e2, int *ifirst,
		int *ilast, double *rtol, int *offset, double *w, double *werr,
		double *work, int *iwork, double *pivmin, double *spdiam, int *info) {
	/* System generated locals */
	int i__1, i__2;
	double d__1, d__2;


	/* Local variables */
	int i__, j, k, p;
	double s;
	int i1, i2, ii;
	double fac, mid;
	int cnt;
	double tmp, left;
	int iter, nint, prev, next, savi1;
	double right, width, dplus;
	int olnint, maxitr;

	/*  -- LAPACK auxiliary routine (version 3.2) -- */
	/*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
	/*     November 2006 */

	/*     .. Scalar Arguments .. */
	/*     .. */
	/*     .. Array Arguments .. */
	/*     .. */

	/*  Purpose */
	/*  ======= */

	/*  Given the initial eigenvalue approximations of T, DLARRJ */
	/*  does  bisection to refine the eigenvalues of T, */
	/*  W( IFIRST-OFFSET ) through W( ILAST-OFFSET ), to more accuracy. Initial */
	/*  guesses for these eigenvalues are input in W, the corresponding estimate */
	/*  of the error in these guesses in WERR. During bisection, intervals */
	/*  [left, right] are maintained by storing their mid-points and */
	/*  semi-widths in the arrays W and WERR respectively. */

	/*  Arguments */
	/*  ========= */

	/*  N       (input) int */
	/*          The order of the matrix. */

	/*  D       (input) DOUBLE PRECISION array, dimension (N) */
	/*          The N diagonal elements of T. */

	/*  E2      (input) DOUBLE PRECISION array, dimension (N-1) */
	/*          The Squares of the (N-1) subdiagonal elements of T. */

	/*  IFIRST  (input) int */
	/*          The index of the first eigenvalue to be computed. */

	/*  ILAST   (input) int */
	/*          The index of the last eigenvalue to be computed. */

	/*  RTOL   (input) DOUBLE PRECISION */
	/*          Tolerance for the convergence of the bisection intervals. */
	/*          An interval [LEFT,RIGHT] has converged if */
	/*          RIGHT-LEFT.LT.RTOL*MAX(|LEFT|,|RIGHT|). */

	/*  OFFSET  (input) int */
	/*          Offset for the arrays W and WERR, i.e., the IFIRST-OFFSET */
	/*          through ILAST-OFFSET elements of these arrays are to be used. */

	/*  W       (input/output) DOUBLE PRECISION array, dimension (N) */
	/*          On input, W( IFIRST-OFFSET ) through W( ILAST-OFFSET ) are */
	/*          estimates of the eigenvalues of L D L^T indexed IFIRST through */
	/*          ILAST. */
	/*          On output, these estimates are refined. */

	/*  WERR    (input/output) DOUBLE PRECISION array, dimension (N) */
	/*          On input, WERR( IFIRST-OFFSET ) through WERR( ILAST-OFFSET ) are */
	/*          the errors in the estimates of the corresponding elements in W. */
	/*          On output, these errors are refined. */

	/*  WORK    (workspace) DOUBLE PRECISION array, dimension (2*N) */
	/*          Workspace. */

	/*  IWORK   (workspace) int array, dimension (2*N) */
	/*          Workspace. */

	/*  PIVMIN  (input) DOUBLE PRECISION */
	/*          The minimum pivot in the Sturm sequence for T. */

	/*  SPDIAM  (input) DOUBLE PRECISION */
	/*          The spectral diameter of T. */

	/*  INFO    (output) int */
	/*          Error flag. */

	/*  Further Details */
	/*  =============== */

	/*  Based on contributions by */
	/*     Beresford Parlett, University of California, Berkeley, USA */
	/*     Jim Demmel, University of California, Berkeley, USA */
	/*     Inderjit Dhillon, University of Texas, Austin, USA */
	/*     Osni Marques, LBNL/NERSC, USA */
	/*     Christof Voemel, University of California, Berkeley, USA */

	/*  ===================================================================== */

	/*     .. Parameters .. */
	/*     .. */
	/*     .. Local Scalars .. */

	/*     .. */
	/*     .. Intrinsic Functions .. */
	/*     .. */
	/*     .. Executable Statements .. */

	/* Parameter adjustments */
	--iwork;
	--work;
	--werr;
	--w;
	--e2;
	--d__;

	/* Function Body */
	*info = 0;

	maxitr = (int) ((log(*spdiam + *pivmin) - log(*pivmin)) / log(2.)) + 2;

	/*     Initialize unconverged intervals in [ WORK(2*I-1), WORK(2*I) ]. */
	/*     The Sturm Count, Count( WORK(2*I-1) ) is arranged to be I-1, while */
	/*     Count( WORK(2*I) ) is stored in IWORK( 2*I ). The int IWORK( 2*I-1 ) */
	/*     for an unconverged interval is set to the index of the next unconverged */
	/*     interval, and is -1 or 0 for a converged interval. Thus a linked */
	/*     list of unconverged intervals is set up. */

	i1 = *ifirst;
	i2 = *ilast;
	/*     The number of unconverged intervals */
	nint = 0;
	/*     The last unconverged interval found */
	prev = 0;
	i__1 = i2;
	for (i__ = i1; i__ <= i__1; ++i__) {
		k = i__ << 1;
		ii = i__ - *offset;
		left = w[ii] - werr[ii];
		mid = w[ii];
		right = w[ii] + werr[ii];
		width = right - mid;
		/* Computing MAX */
		d__1 = fabs(left), d__2 = fabs(right);
		tmp = max(d__1, d__2);
		/*        The following test prevents the test of converged intervals */
		if (width < *rtol * tmp) {
			/*           This interval has already converged and does not need refinement. */
			/*           (Note that the gaps might change through refining the */
			/*            eigenvalues, however, they can only get bigger.) */
			/*           Remove it from the list. */
			iwork[k - 1] = -1;
			/*           Make sure that I1 always points to the first unconverged interval */
			if (i__ == i1 && i__ < i2) {
				i1 = i__ + 1;
			}
			if (prev >= i1 && i__ <= i2) {
				iwork[(prev << 1) - 1] = i__ + 1;
			}
		} else {
			/*           unconverged interval found */
			prev = i__;
			/*           Make sure that [LEFT,RIGHT] contains the desired eigenvalue */

			/*           Do while( CNT(LEFT).GT.I-1 ) */

			fac = 1.;
			L20: cnt = 0;
			s = left;
			dplus = d__[1] - s;
			if (dplus < 0.) {
				++cnt;
			}
			i__2 = *n;
			for (j = 2; j <= i__2; ++j) {
				dplus = d__[j] - s - e2[j - 1] / dplus;
				if (dplus < 0.) {
					++cnt;
				}
				/* L30: */
			}
			if (cnt > i__ - 1) {
				left -= werr[ii] * fac;
				fac *= 2.;
				goto L20;
			}

			/*           Do while( CNT(RIGHT).LT.I ) */

			fac = 1.;
			L50: cnt = 0;
			s = right;
			dplus = d__[1] - s;
			if (dplus < 0.) {
				++cnt;
			}
			i__2 = *n;
			for (j = 2; j <= i__2; ++j) {
				dplus = d__[j] - s - e2[j - 1] / dplus;
				if (dplus < 0.) {
					++cnt;
				}
				/* L60: */
			}
			if (cnt < i__) {
				right += werr[ii] * fac;
				fac *= 2.;
				goto L50;
			}
			++nint;
			iwork[k - 1] = i__ + 1;
			iwork[k] = cnt;
		}
		work[k - 1] = left;
		work[k] = right;
		/* L75: */
	}
	savi1 = i1;

	/*     Do while( NINT.GT.0 ), i.e. there are still unconverged intervals */
	/*     and while (ITER.LT.MAXITR) */

	iter = 0;
	L80: prev = i1 - 1;
	i__ = i1;
	olnint = nint;
	i__1 = olnint;
	for (p = 1; p <= i__1; ++p) {
		k = i__ << 1;
		ii = i__ - *offset;
		next = iwork[k - 1];
		left = work[k - 1];
		right = work[k];
		mid = (left + right) * .5;
		/*        semiwidth of interval */
		width = right - mid;
		/* Computing MAX */
		d__1 = fabs(left), d__2 = fabs(right);
		tmp = max(d__1, d__2);
		if (width < *rtol * tmp || iter == maxitr) {
			/*           reduce number of unconverged intervals */
			--nint;
			/*           Mark interval as converged. */
			iwork[k - 1] = 0;
			if (i1 == i__) {
				i1 = next;
			} else {
				/*              Prev holds the last unconverged interval previously examined */
				if (prev >= i1) {
					iwork[(prev << 1) - 1] = next;
				}
			}
			i__ = next;
			goto L100;
		}
		prev = i__;

		/*        Perform one bisection step */

		cnt = 0;
		s = mid;
		dplus = d__[1] - s;
		if (dplus < 0.) {
			++cnt;
		}
		i__2 = *n;
		for (j = 2; j <= i__2; ++j) {
			dplus = d__[j] - s - e2[j - 1] / dplus;
			if (dplus < 0.) {
				++cnt;
			}
			/* L90: */
		}
		if (cnt <= i__ - 1) {
			work[k - 1] = mid;
		} else {
			work[k] = mid;
		}
		i__ = next;
		L100: ;
	}
	++iter;
	/*     do another loop if there are still unconverged intervals */
	/*     However, in the last iteration, all intervals are accepted */
	/*     since this is the best we can do. */
	if (nint > 0 && iter <= maxitr) {
		goto L80;
	}

	/*     At this point, all the intervals have converged */
	i__1 = *ilast;
	for (i__ = savi1; i__ <= i__1; ++i__) {
		k = i__ << 1;
		ii = i__ - *offset;
		/*        All intervals marked by '0' have been refined. */
		if (iwork[k - 1] == 0) {
			w[ii] = (work[k - 1] + work[k]) * .5;
			werr[ii] = work[k] - w[ii];
		}
		/* L110: */
	}

	return 0;

	/*     End of DLARRJ */

} /* dlarrj_ */
